<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script></script>
    <meta>
</head>
<body>

<script>
    function Fish(){
        this.name = 'frank';
        this.say=function(){
            console.log(this.name)
        }
    }
    var f = new Fish();
    console.log(f);

    function DSFish(){

    }
    DSFish.prototype = new Fish();
    var ds= new DSFish();
</script>
</body>
</html>